In this article I’ll show you how to refine the notification of an event by creating a detailed data report.
This post closes the basic part of the project. There will be other articles related to the Azure Veneziano project, but they are mostly additional components and enrichment to the base system.

The problem.

When the system alerts you about, for instance, the outside temperature which is getting higher the more is sunny, I believe there’s no need of any detail on.
However, the things could turn dramatically different if you receive a notification such as “your aquarium temperature is greater than 35°C”. Unless you have very special fishes, there are just two possibilities:

the fishes are in a serious danger, or

something is broken (e.g. the probe, the wiring, etc).

In the first case, there’s no other way than making some immediate action before the fishes die. In the second case, you could even tolerate the failure knowing that the system is unable to work properly, until it will be fixed.
However, if you’re at the mall, for instance, and you receive such a mail: what would you do? Better question: how to know what kind of problem is? Also, how the system evolved before facing the issue?
Of course you can add “redundancy” to the telemetry system, so that you’ll have more info (and that’s always a good thing). For instance, you could use two probes instead of just one. Since the fishes life is in danger, a probe more is actually a natural choice.
Anyway, if you receive a simple message like “the water temperature is 55°C”, you can’t understand where the problem is. A bit different if the message shows you the “evolution” of that temperature. If the evolution acts like a “step”, where the temperature rises to a prohibitive value in a few time, then it’s probably something broken in the hardware. Reasonably, the aquarium tank can’t get hotter in minutes or less.
All that depicts a scenery where a collection of values over time is an useful “attachment” to the alerting message. Here, the target is representing the data collected as both chart and table fashion.

Looking for the right library.

As for report I mean a simple document, which contains details on what happened. For this project, we’ll create a three-pages report with a couple of charts, and also a brief tabular history of the collected data.
Once again, I’d like to remember that this project is a kind of “sandbox” for something professional. Thus, I prefer to try “a bit of everything” in order to take practice with the environment: Azure at first, then several accessories. For this reason, I wanted the ability to create the report document in both Word- and PDF-format.
Around the Internet there is plenty of creation and conversion tools, but most of them are very expensive. In a professional context that would be feasible, but of course isn’t acceptable for any home/hobby target.

Finally, I bumped against the Spire.Doc Free-edition by e-iceblue.
They offer a complete suite of tools for many standard formats. Despite their regular price is off the hobbyist-pocket, they also offer the Free-Edition option. I tested only the Spire.Doc component (tailored for the Word documents), and the limitations are pretty acceptable. At first glance some limitation looks like a wall, but it’s easy to play around the APIs and to find the right trick!
Moreover, when I had some trouble with the library, I asked them an help by the forum, and the answer came very quickly.

How to create your own report.

The usage of the Spire.Doc library is very simple, however I created a series of support functions in order to specialize the code for the report creation.
It’s worthwhile to say that the generated report is meant as “attachment” for the notification mail, so the below code is called automatically when the logic sends a mail.
The only thing the logic should specify is the list of useful variables to detail in the report. That’s an obvious requirement, especially when you deal with many variables.

Then, since the cover is made up from a well-defined template, its creation is straightful immediately after the document model. I also used an extension-method pattern so that the various function invocation will shape as fluent-fashion.

What’s behind?
There’s nothing secret. Those functions are only a shortcut for easy manipulating a report, but anyone could create his/her own functions.
The document generation creates a Document instance, defines its properties as well as the available styles. Please, note that the library comes with several pre-defined styles, but I wanted to create my own:

So far, so well.
If you wonder what’s the result at this point, here is a snapshot:

Please, since I was running out of logo pictures of my “Home Company”, I turned for a picture of my boss, far serious than many CEOs all around the world.
Hope you love her!

Let’s turn page: here the work begins to get harder.
The second page should give a brief overview of what happened at the very beginning. At first glance, the reader should mean WHY the mail has been sent. That’s still pretty easy to do, because it’s just a bunch of “Paragraph” to insert into the current page.

Since some lines of text shouldn’t steal much space on the page, I want to place a couple of charts about the most recent evolution of the selected variables.
Later we’ll cover how the chart generation works.

It’s worthwhile noting that I didn’t use the Table APIs as the library exposes. Again, I wanted to play around the library to face its flexibility.
At the end, I used the “tabulation-technique” and I must admit that the Spire.Doc library is very easy yet very powerful to use.

The very last thing to do is obviously to save the composed document. As described earlier, there’s no a permanent place where the document is stored, rather it is streamed directly as attachment to the mail.
Here below there is the snippet for both the Word- and the PDF-formats, so that the mail will carry two identical reports, then the user can open with the favorite reader.

How does it appear on my phone?

I believe it’s funny trying to read a data report on a phone. I mean that even on a relatively small screen you can read the same things as you were on a PC. Well, it’s not as easy as it looks, but I really love it as a start point!

Nice enough!…

Some words about the PDF document creation.

As you know, the Azure Veneziano project has been built against a totally free environment. By the way, the free websites that Azure offers where this WebJob runs, come with some limitation. In this case, the Spire.Doc library require GDI/GDI+ for the PDF generation, and that’s unavailable/unsupported by the Azure free context.
I fully tested the PDF generation in a desktop application, and the result was always perfect. However, if you need the Azure-side PDF generation, I believe there are at least two choices:

move the WebJob to a Cloud Service/VM (or any paid context) as suggested here;

leverage some online services such as this one, which offers up to 500 documents per months fro free.

The chart generation.

There are plenty of chart libraries on the web, both free and commercial. However, I created my own charting library because I needed several features that they’re hard to find all around. More specifically, my charting library is tailored for our industrial supervisory control systems, where the requirements are very different from, for instance, financial applications.
For the Azure Veneziano project, I took a small fraction of this library, but far enough to render multi-plots, multi-axes, WPF charts.

The usage is pretty simple, although an user may find uselessly verbose the code. Again, that’s because the original library is full-featured, and many functions don’t come easy without a certain dose of source code.

The only “strange” thing is that we actually DO NOT HAVE a WPF application, but something like a Console application, “hidden” somewhere in the Azure cloud.
However, this isn’t surprising at all, because the above code instantiate an UserControl as container for the chart. Once the chart model setup is done, there’s a “fake” measuring+arranging pass, followed by a final rendering against the control’s face.
The very final step is to capture the visual of this usercontrol and save as a bitmap image (PNG format). This image is inserted in the document as usual

Just a quick-and-dirty solution for solving the tedious problem of the numpad’s decimal-point insertion where the culture require something different than a dot “.”.

The problem.

Many of you, who aren’t using a dot as decimal separator, maybe noticed that the character issued by the numeric-pad is always a doe, regardless the OS settings. In Italy, for instance, we’re using the comma as decimal separator.
You know, if you type the wrong character, the number won’t be recognized as valid (sometimes even worse, because it’s mistaken as valid).
If you try to open Notepad or any raw-input application, you’ll notice that there’s no way to “hack” the Windows settings in order to correctly input the numeric-pad “point” as a comma. By the way, if you enter a number in Microsoft Excel or so, the character is actually a comma.
Looks like the translation is something managed by the application.

It’s not so simple, though.
Imagine to write your own application (WPF in my case), and have a series of textboxes. Whereas a textbox used for entering a number (e.g. most physical units) would be fine having a “translation” to a comma, when another textbox used for an IP-pattern, clearly should *NOT* be translated any time.
Looks like that some countries use a different punctuation for generic numbers and for currency: my “neighbor” friends of Switzerland do use the comma for any number but currency, where the dot is preferred.

The solution.

Here is a solution, but I believe is difficult to satisfy all the developers’ habits. I just opted for a simple attached-property, as “behavior” to any TextBoxBase object, which “intercepts” the Decimal key (the numpad’s DP) and replaces it with the proper one.

The code is rather simple, so I think would be useless chatting more.
The only worthwhile point is regarding the “async” pattern in the key-replace function. I just wanted to leave the originating event (PreviewKeyDown) a bit of time to finish before adding another (possible) event. Honestly, I don’t know whether that’s really necessary: the async-await pattern comes easy and reliable, so I prefer to keep the code safer. Feel free to improve the it.

Here is a simple trick for simulating the shared-sizing feature of the WPF Grid even in a StackPanel fashion.

Basically, you can have several panels, each one in a separate visual fragment, and “synchronize” their children height (or width, when horizontally-oriented).
A short video explains better than thousands of words.

The solution is pretty simple. Since the Grid already offers such a feature, the trick is leveraging it instead a “real” StackPanel. Otherwise, the mechanism for managing the shared-size scopes is rather complex. As for “complex” I mean that you should keep all the scrolling and virtualization features which is part of a StackPanel, and that’s rather complex.
The resulting StackPanel-surrogate code is very simple:

After loooooooong time, the Cet MicroWPF repository is publicly available on CodePlex.
The awaited release comes with a (decent) tutorial, where you may follow step-by-step how to create a nice graphical UI for your Netduino. Many more is still to do, but of sure there are enough stuffs to have some fun!

The spare time is few, but step by step the target is getting closer.
It’s a been I’ve started playing around the FTDI FT800 Eve board, and it must admit it is awesome. If you need a quick solution to add a small touch display to your *duino board, the Eve is something you should consider.

You know, I love Netduino and C#. That’s because I chose to play with the display using Netduino (Plus 2), and honestly I’d expected a pretty bad performance. Instead, the graphic engine of the Eve can be easily driven via SPI from any board. That is, the SPI on Netduino is fast, very fast.

My goal is creating a small library for helping many users to create small and funny home/hobby projects with the Netduino and the Eve display boards. Since I love the classic WPF, how could I avoid to inspire from them?

Micro WPF

If you know WPF, many concepts would come easier. Otherwise, I recommend to take a look to the documentation, tutorials and whatever you want. Even if you don’t harm with a PC, rather with the Windows Store/Phone APIs, the approach here isn’t too far from.
The “WPF” term for a simple Netduino is clearly abused. Here is just the visual approach, the XAML-like approach to create the UI, and -yes- the same ability to create your own controls: MeasureOverride and ArrangeOverride.
That’s not all.
If you have any visual application in mind with Netduino+Eve (e.g. a climate control, IoT client, etc), then probably you’d need some kind of navigation service across several pages. That’s the most modern UI experience, on every device: PC, tablets, and phones.

I still don’t write what the library will offer, because it’s just something made for fun: for helping hobbists and even students working with a UI on a such small board as Netduino is.
For sure, there are NOT (nor in the future):

data binding

XAML parsing (the tree has to be created programmatically)

styling

the remaining 99.99% of regular WPF…

An example of layout

The most versatile yet complex layout control is the Grid, but it seems working fine.
Let’s take this sample XAML:

Source code

This is a double-purpose post: a simple hack around the WPF ComboBox, and a subtle bug in it.
The short video explains both the problems way better than my words could do.

Most of the times, I use the ComboBox as a simple drop-down list. That works perfectly and that’s why I never bumped against the problems around.
This time I needed a real ComboBox, that is the ability to select from a drop-down list as always, but with the editable box as well. More precisely, I wanted the following behaviors:

the user can drop the list and select any item (that’s the usual feature)

the user can type in an existent item or a new one

as the user type in the selection box, the drop-down should open

(future) the drop-down list should be filtered upon the actual text typed in the selection box

The first two points are already available in the standard ComboBox control, while the fourth is just a wish for the (near) future. The problems arose with the third point, because the simplest yet intuitive way I used yielded a nice exception!

The base for the test.

Nothing fancy here: just a collection of objects, very simple. The classic “Person” with an “ID” (why didn’t I named so?):

The deal is populating the combo-box with such a data-set, then testing for a numeric input so that the drop-down part should arrange accordingly. As a (future) bonus, the list should be filtered upon the actual number. That should facilitate the user when he/she has to enter a non-existent ID.
On the XAML-side the base is something like this:

Although everything seemed going fine (no errors), once you click with the left mouse button in the selection box, a nasty “StackOverflow” exception is suddenly raised. No matter whether the application is creates as “Debug” or “Release”: the error seems very stable.

At first glance it’s not clear why it happens, and not how to solve or even around it. Also because the actual exception looks as raised in a very deep layer, below the managed. However, that’s just what I suppose.
The second attempt gave me a clearer idea.

Second attempt: better, but not solved yet.

The second attempt was focus on find any (decent) workaround to the bug. Internet didn’t give more help, so I had to find something reliable to make the ComboBox working.
The hint was just on the “stack overflow”, because most of the times it’s a recursive problem. Again, many times you generate such a exception when there are circular calls, that fill the stack sooner. So, let’s give the UI a “breath”: a small delay, so that a routine can complete before actually calling the next one.
Here is the trick:

Well, the exception wasn’t raised any more, but…AW!…the interaction result was not the expected.
Since the drop-down part is actually a borderless “Window” object, it tries to capture the mouse, at least until some kind of mouse action is worthwhile to be captured. As soon, the mouse click outside its client area, the down-down window closes, but the click is “lost”. That is, there’s no (easy) way to interact with the “real” window, so even an attempt to close the application looks impossible.

Despite this trick did not solved the problem, at least it clears *why* the exception is raised in the previous scenario. As soon the selection box is highlighted, the trigger starts the opening of the drop-down. However, the opening of this new child-window would captures the user-input, moving the focus off the selection box. However, the focus is restored to the selection box, and the condition will trigger again the drop-down opening.

Third attempt: all right!

The final solution isn’t much different than the previous attempt: simply avoid the “IsSelectionBoxHighlighted” property…

Conclusion.

This is another post about the hacking of the standard WPF GridView typically used with(in) the ListView. If you missed anything about my previous three article on it, please have a look here.
By using the hacked component in some real projects, I discovered that something was missing, and something else could be improved. In particular, here are a couple of features making my GridViewEx almost complete (well…not perfect yet!)

XAML-defined columns.

The GridViewEx approach was based on a GridViewColumn wrapper. The host application should add as many wrappers as needed, and the real columns will be created (and synchronized) accordingly. This approach is basically the MVVM pattern, and yields the ability to manipulate the visual columns with ease and flexibility.
However, that’s not always an acceptable usage: the XAML-way to define templates and styles is far better than the classic code. Well, I wished to find a solution as a compromise between the MVVM flexibility and the XAML power.
The solution I chose is pretty easy: an extra columns “back” synchronization, which operates when there’s no ambiguity between the XAML and the MVVM collections content. The legacy MVVM columns management is still alive and full compatible. However, when the MVVM is bound “empty” the XAML columns definition will be taken in account.
Here follows the code added to the GridViewEx class.

The above method is called once only, at the moment of the binding to a new wrapper collection. As the code shows, if there’s no wrappers, the defined XAML GridViewColumn are automatically converted to wrappers. Hereinafter the game plays as usual.

The column’s setup has been moved off the existent Align method, to a dedicated one in order to be used both in the forward- and in the back-alignment of the columns’ collection.

Per-column defined cell content alignment.

Sometime is useful to define the alignment (horizontal and vertical) of a cell content. Unfortunately the native GridView offers no help about this feature, and the only way to control the cell behavior is via the ListViewItem styling.
To be clear, none of the below approaches will align the text content to the right edge of the respective cells.

That’s because the template-created content is actually hosted in a ContentPresenter object. The GridView creates as many ContentPresenters as the columns are, and the user’s control over these components is very limited. Please note that the ContentPresenters are created always but when you bind the cell’s content via a simpler DisplayMemberBinding. In that case, a simple TextBlock is created instead.
As said, the only way to control the alignment of the hosted ContentPresenters is by settings the HorizontalContentAlignment (or VerticalContentAlignment) in the ListViewItem style. In other words, you could style the rows as follows:

The result is as expected, but involves all the cells, without any control on a specific column.

This behavior is predefined in the GridViewRowPresenter, which is part of the default rows styling. The most straightforward way to take the control over the row’s cell presenters is creating (or deriving) a custom GridViewRowPresenter, then re-styling the ListViewItem. However, I would avoid to touch any of the Windows’ default styles.

The solution I used takes advantage of a couple of Attachable DependencyProperty: one for each alignment orientation.
The attached DP comes in aid because it can be stuck anywhere in the logical tree, and that’s helping to reach the hidden visual element. The basic idea is right on the attaching event of the DP: at that time the visual tree is walked up, up to the “original” GridViewRowPresenter. The immediate-child of that presenter is the sought ContentPresenter, and the alignment properties are fully exposed.

Conclusions.

Hacking. Far funnier than digging around for hours looking for a ready-to-go solution, which (we do know) does not exist.
I loved this series of hacking around the GridView, because it showed me that even a very simple component as the (ListView plus the) GridView is, yields a lot of power by just learning a bit on how its core works.